Weird cooling system issue
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Pro
Joined: Mar 2013
Posts: 698
Likes: 162
From: Huntington WV
Weird cooling system issue
So I'm prowling around under the hood of my new to me 93. Engine is cold and I notice the lower radiator hose is sucked together. I open the radiator cap and it releases some, but not entirely. Car runs fine and with normal operating temps. Is it just as simple as getting a new radiator cap or should I be looking at something else?
Last edited by Polo Vert; Oct 11, 2024 at 11:26 AM.
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,082
From: So Cal
2023 C4 of the Year Finalist - Unmodified
Remember guys, on an LT1, the lower hose (inlet) is regulated by the thermostat. The LT1 is a "cold-side" thermostat. As the system cools down, the thermostat completely closes off the lower hose. While both upper and lower hoses should collaps equally, the upper hoses are shorter and better supported, so they may not collapse to the degree that the lower one will.
The expansion tank cap has a stuck vacuum relief valve. Remove the cap and look at the bottom of it. There's a little 'disc' on the larger disc. That little disc (about 1/2" in diameter) is the vacuum relief valve. Use a razor knife blade to gently get under the little disc and un-stick it. If it is indeed stuck, and you can free it, try it. You won't have to replace the cap.
The expansion tank cap has a stuck vacuum relief valve. Remove the cap and look at the bottom of it. There's a little 'disc' on the larger disc. That little disc (about 1/2" in diameter) is the vacuum relief valve. Use a razor knife blade to gently get under the little disc and un-stick it. If it is indeed stuck, and you can free it, try it. You won't have to replace the cap.
